Highly tunable extinction properties based on dual symmetry breaking in multilayer nanoshells

In this study, we have demonstrated that the multilayer nanoshells with dual symmetry breaking including the offset both dielectric layer and Au core can realize highly tunable extinction properties which are sensitively dependent on the relative offset direction between the Au core and dielectric layer. By controlling the offset direction of the Au core relative to the dielectric layer, the distinct multipeaked spectra with highly tunable multiple plasmon resonances can be excited selectively. The plasmon hybridization theory is applied to elucidate the origin of these resonances from the interactions of an admixture of both primitive and multipolar modes between the core and the broken nanoshell. Furthermore, the electromagnetic hot spots in dual symmetry breaking is accompanied by local-field enhancements, depending on the offset direction of the Au core relative to the dielectric layer, significantly larger than those obtainable for the single broken nanoparticle case.